How can I enable guests to participate in a chat activity?

(The guest role has some special functionality, for example when a guest attempts to participate in a chat, they obtain the message "The chat is not open to guests. Would you like to log in now with a full user account?". Despite the permissions interface suggesting otherwise, it's not possible to modify the guest role to allow guests to participate in chat activities.)

How can I use audio chat?

Moodle itself does not yet include an audio chat solution, due to the large server requirements to implement a standalone solution.

However, there is a choice of free third party modules that you can install into your Moodle to achieve this: